This invention relates to balloons and, in particular, to a balloon having a self-sealing valve.
Exemplary of presently existing self-sealing balloons is the balloon shown in U.S. Pat. No. 4,708,167 having a valve positioned in and bonded to the stem of the balloon. The valve is formed from two valve sheets bonded together to define a valve inlet and a valve outlet, and the valve is so positioned in the balloon that the valve inlet extends outwardly beyond the balloon stem. The inside surface of one of the valve sheets is coated with a bond-resistant coating to prevent bonding of the valve sheets together during bonding of the valve to the balloon. The valve sheets are generally thin and therefore often difficult to separate at the valve inlet, making it difficult to insert a gas supply nozzle to inflate the balloon. Also, although the self-sealing valve functions to resist leakage of gas out the stem of the balloon without permanently sealing the stem, in some circumstances it is desirable to permanently close the valve by a heat-seal across the balloon stem after inflation of the balloon. This cannot be accomplished in the aforementioned prior art balloon since the bond-resistant coating on the valve prevents heat-sealing of the valve in the stem area of the balloon.
In another prior art balloon, the valve lies entirely within the balloon and extends from a portion of the stem adjacent the body of the balloon into the body. A disadvantage of this balloon is that the valve is not visible when the balloon is assembled. If the valve is not properly positioned in the balloon during assembly--e.g., due to a malfunction in the assembly process--the defect in the balloon cannot be visually detected. Also, since the valve is not positioned in the end of the stem, the thickness of the stem is no greater than the thickness of the balloon sheet. Thus, a string tied to the end of the stem may tear the stem because the stem is not reinforced.